CPC Main Group
E21D 11/00 Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling (E21D15/00 - E21D23/00 take precedence; specially for shafts E21D5/00; ; lining pressure water galleries, linings therefor E02B9/06)
Filing statistics
CPC E21D 11/00 belongs to the parent subclass E21D, which recorded 43,973 patent applications worldwide between 2013 and 2023. Annual filings grew from 1,000 in 2013 to 6,074 in 2023 (+507%), peaking at 6,255 applications in 2020. The most active applicants in class E21 are HALLIBURTON ENERGY SERVICES GROUP (27,652 applications), SAUDI ARABIAN OIL COMPANY (7,755 applications) and PETROCHINA COMPANY (7,025 applications).
Source: EPO PATSTAT, worldwide filings
7 direct subcodes
Child Classifications
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- E21D 11/02 Lining predominantly with wood
- E21D 11/04 Lining with building materials (E21D11/02, E21D11/14 take precedence )
- E21D 11/14 Lining predominantly with metal
- E21D 11/38 Waterproofing (in general E02D31/00); Heat insulating; Soundproofing; Electric insulating (for building constructions in general E04B1/62)
- E21D 11/40 Devices or apparatus specially adapted for handling or placing units of linings for tunnels or galleries
Top Applicants
Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT
- HALLIBURTON ENERGY SERVICES GROUP US 27,652
- SAUDI ARABIAN OIL COMPANY SA 7,755
- PETROCHINA COMPANY 7,025
- BAKER HUGHES US 6,589
- SCHLUMBERGER TECHNOLOGY US 6,151
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 4,443
- SCHLUMBERGER TECHNOLOGY NL 4,255
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 3,991
- SERVICES PETROLIERS SCHLUMBERGER FR 3,300
- SCHLUMBERGER CANADA CA 3,086